Long-lasting spiral density waves occur in the disk of a spiral galaxy when
A) the spiral merges with another galaxy.
B) the galaxy is too close.
C) the galaxy's disk is regularly disturbed.
D) None of the above

Question

Quizplus · Accepted Answer

Long-lasting spiral density waves occur in the disk of a spiral galaxy when the galaxy's disk is regularly disturbed. This can happen due to interactions with other galaxies or through the inflow of gas from the intergalactic medium. As the gas clouds are disturbed or compressed, they can trigger the formation of new stars, which can then sustain the spiral structure for millions of years.

Long-Lasting Spiral Density Waves Occur in the Disk of a Spiral